A number of industrial processes involve the introduction of a loose solid feedstock into a pressurized reaction chamber or vessel. Unless the process is limited to batch operation this may require that the feedstock be pressurized and forced into the reaction vessel while the reaction vessel is maintained at elevated pressure, and possibly also while maintained at elevated temperature. In a continuous process with a pure liquid or a compact solid this may be relatively straightforward. Even for a slurry, or for two-phased flow where solids are suspended in a carrier fluid, this may be possible without undue difficulty.
However, the compaction and pressurization of a rather porous, substantially dry solid, which may have the form of chips or flakes, or strands, may present a challenge. For example, these flakes or chips may be ligneous by-products of a forestry or agricultural activity. Earlier attempts to address this challenge are shown and described, for example, in U.S. Pat. No. 4,119,025 of Brown, issued Oct. 10, 1978; U.S. Pat. No. 4,947,743 of Brown et al., issued Aug. 14, 1990; and PCT Application PCT/CA99/00679 of Burke et al., published as WO 00/07806 published Feb. 17, 2000, the subject matter of all of these documents being incorporated herein by reference. At the end of the process, the loose, fibrous, typically organic material leaves the reaction chamber through a discharge assembly of some kind, whence it is collected for further use or processing. To the extent that the process feedstock is then to be used as an input to a subsequent process, such as a biological digestion process, it may be desirable that the fibrous material be finely expanded.